U.S. patent application number 12/017598 was filed with the patent office on 2012-05-24 for two-dimensional patterning employing self-assembled material.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Timothy J. Dalton, Bruce B. Doris, Ho-Cheol Kim, Carl Radens.
Application Number | 20120129357 12/017598 |
Document ID | / |
Family ID | 40901402 |
Filed Date | 2012-05-24 |
United States Patent
Application |
20120129357 |
Kind Code |
A1 |
Dalton; Timothy J. ; et
al. |
May 24, 2012 |
TWO-DIMENSIONAL PATTERNING EMPLOYING SELF-ASSEMBLED MATERIAL
Abstract
A first nanoscale self-aligned self-assembled nested line
structure having a sublithographic width and a sublithographic
spacing and running along a first direction is formed from first
self-assembling block copolymers within a first layer. The first
layer is filled with a filler material and a second layer is
deposited above the first layer containing the first nanoscale
nested line structure. A second nanoscale self-aligned
self-assembled nested line structure having a sublithographic width
and a sublithographic spacing and running in a second direction is
formed from second self-assembling block copolymers within the
second layer. The composite pattern of the first nanoscale nested
line structure and the second nanoscale nested line structure is
transferred into an underlayer beneath the first layer to form an
array of structures containing periodicity in two directions.
Inventors: |
Dalton; Timothy J.;
(Ridgefield, CT) ; Doris; Bruce B.; (Brewster,
NY) ; Kim; Ho-Cheol; (San Jose, CA) ; Radens;
Carl; (Lagrangeville, NY) |
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
Armonk
NY
|
Family ID: |
40901402 |
Appl. No.: |
12/017598 |
Filed: |
January 22, 2008 |
Current U.S.
Class: |
438/780 ;
257/E21.24; 977/887 |
Current CPC
Class: |
H01L 21/0337 20130101;
B82Y 30/00 20130101; B81C 1/00031 20130101; Y10T 428/24612
20150115; B82Y 10/00 20130101; B81C 2201/0149 20130101; H01L
21/0338 20130101 |
Class at
Publication: |
438/780 ;
977/887; 257/E21.24 |
International
Class: |
H01L 21/31 20060101
H01L021/31 |
Claims
1. A method of forming a nanoscale pattern on a substrate, said
method comprising: forming a first recessed region having a bottom
surface that contiguously extends between two parallel first
lengthwise edges on a first layer on a substrate; forming a first
nanoscale self-assembled self-aligned structure containing at least
one first line having a first sublithographic width and having
first line edges parallel to said two parallel first lengthwise
edges of said first recessed region; forming a second layer as a
blanket layer that contiguously extends over said first nanoscale
self-assembled self-aligned structure and over said first layer,
wherein said bottom surface and said two parallel first lengthwise
edges are located at identical locations relative to said substrate
after said forming of said second layer as upon formation of said
first recessed region; forming a second recessed region having two
parallel second lengthwise edges on said second layer, wherein an
angle between said two parallel first lengthwise edges and said two
parallel second lengthwise edges is greater than zero; and forming
a second nanoscale self-assembled self-aligned structure containing
at least one second line having a second sublithographic width and
having second line edges parallel to said two parallel second
lengthwise edges of said first recessed region.
2. The method of claim 1, wherein said first nanoscale
self-assembled self-aligned structure is located at or beneath a
top surface of said first layer.
3. The method of claim 1, wherein said first nanoscale
self-assembled self-aligned structure is located at or beneath a
top surface of said second layer.
4. The method of claim 1, wherein said method comprises applying a
first non-photosensitive polymeric resist comprising a first
polymeric component and a second polymeric component in said first
recessed region, wherein said at least one first line comprises
said first polymeric component.
5. The method of claim 4, further comprising: forming at least one
third line having a third sublithographic width, comprising said
second polymeric component, and laterally abutting said at least
one first line in said first recessed region; and removing said at
least one third line selective to said at least one first line and
said first layer.
6. The method of claim 5, further comprising filling a space formed
by removal of said at least one third line with a filler material
that is different from said first non-photosensitive polymeric
resist.
7. The method of claim 1, further comprising applying a second
non-photosensitive polymeric resist comprising a third polymeric
component and a fourth polymeric component in said second recessed
region, wherein said at least one second line comprises said third
polymeric component.
8. The method of claim 6, further comprising: forming at least one
fourth line having a fourth sublithographic width, comprising said
fourth polymeric component, and laterally abutting said at least
one second line in said second recessed region; and removing said
at least one fourth line selective to said at least one second line
and said second layer.
9. The method of claim 1, wherein said at least one first line
comprises a polymeric component of a first non-photosensitive
polymeric resist and said at least one second line comprises a
polymeric component of a second non-photosensitive polymeric
resist, wherein said method further comprises removing said second
layer selective to said at least one second line.
10. The method of claim 9, further comprising removing said first
layer selective to said at least one first line and said at least
one second line.
11. The method of claim 10, further comprising forming a structure
comprising a two dimensional array of nanoscale trenches in an
underlayer beneath said first layer and on said substrate, wherein
said nanoscale trenches are repeated along a first direction and a
second direction within said two dimensional array, and wherein
each of said nanoscale trenches has a first pair of sidewalls
separated by a first sublithographic distance and a second pair of
sidewalls separated by a second sublithographic distance.
12. The method of claim 11, wherein said first direction is
perpendicular to said two parallel first lengthwise edges, and
wherein said second direction is perpendicular to said two parallel
second lengthwise edges.
13. The method of claim 12, wherein a horizontal cross-sectional
area of said nanoscale trenches is a parallelogram.
14. The method of claim 13, wherein said horizontal cross-sectional
area of said nanoscale trenches is a rectangle.
15-20. (canceled)
21. The method of claim 1, wherein said first nanoscale
self-assembled self-aligned structure further contains at least one
first complementary lamellar structure, wherein said at least one
first line and said at least one first complementary lamellar
structure, upon formation, complementarily fills said first
recessed region.
22. The method of claim 21, further comprising removing said at
least one first complementary lamellar structure from said first
recessed region while said at least first line is not removed.
23. The method of claim 22, wherein portions of said bottom surface
is physically exposed after said removal of said at least one first
complementary lamellar structure.
24. The method of claim 23, further comprising filling a volume
from which said at least one first complementary lamellar structure
is removed with at least one filler portion.
25. The method of claim 22, further comprising depositing a same
material as said second layer within a volume from which said at
least one first complementary lamellar structure is removed,
wherein at least one filler portion filling said volume if formed,
and wherein said at least one filler portion and said second layer
are integrally formed without any manifested physical interface
therebetween.
26. The method of claim 1, wherein an entirety of said second
recessed region is located above, and is vertically spaced from, a
topmost surface of said first layer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to nanoscale
structures, and more particularly to two-dimensional self-assembled
sublithographic nanoscale structures in a regular periodic array
and methods for manufacturing the same.
BACKGROUND OF THE INVENTION
[0002] The use of bottom-up approaches to semiconductor fabrication
has grown in interest within the semiconductor industry. One such
approach utilizes self-assembling block copolymers for generation
of sublithographic ground rule nanometer scale patterns.
[0003] Self-assembling copolymer materials that are capable of
self-organizing into nanometer-scale patterns may be applied within
a recessed region of a template layer to form a nanoscale
structure. Under suitable conditions, the two or more immiscible
polymeric block components separate into two or more different
phases on a nanometer scale, and thereby form ordered patterns of
isolated nano-sized structural units. Such ordered patterns of
isolated nano-sized structural units formed by the self-assembling
block copolymers can be used for fabricating nano-scale structural
units in semiconductor, optical, and magnetic devices. Dimensions
of the structural units so formed are typically in the range of 5
to 40 nm, which are sublithographic (i.e., below the resolution of
the lithographic tools).
[0004] The self-assembling block copolymers are first dissolved in
a suitable solvent system to form a block copolymer solution, which
is then applied onto the surface of an underlayer to form a block
copolymer layer. The self-assembling block copolymers are annealed
at an elevated temperature to form two sets of polymer block
structures containing two different polymeric block components. The
polymeric block structure may be lines or cylinders. One set of
polymer block structures may be embedded in the other set of
polymer block structures, or polymeric block structures belonging
to different sets may alternate. The self-assembling block
copolymers are non-photosensitive resists, of which the patterning
is effected not by photons, i.e., optical radiation, but by
self-assembly under suitable conditions such as an anneal.
[0005] While self-assembled self-aligned nanoscale structure in a
hexagonal array has been known in the art, such a configuration
poses geometrical limitations in placement of device components.
This is particularly so since most semiconductor device arrays and
nanoscale arrays are typically designed in a rectangular array, not
in a hexagonal array.
[0006] In view of the above, there exists a need for a two
dimensional array of self-aligned self-assembled structures in a
rectangular array in which the periodicity of the structure
propagates along two directions having an angle other than 60
degrees therebetween.
[0007] Particularly, there exists a need for a two dimensional
rectangular array of structures having sublithographic spacing and
width in two orthogonal directions.
SUMMARY OF THE INVENTION
[0008] The present invention addresses the needs described above by
providing a rectangular array of nanoscale structures having
sublithographic width and spacing in two different directions, and
methods of manufacturing the same.
[0009] A first nanoscale self-aligned self-assembled nested line
structure having a sublithographic width and a sublithographic
spacing and running along a first direction is formed from first
self-assembling block copolymers within a first layer. The first
layer is filled with a filler material and a second layer is
deposited above the first layer containing the first nanoscale
nested line structure. A second nanoscale self-aligned
self-assembled nested line structure having a sublithographic width
and a sublithographic spacing and running in a second direction is
formed from second self-assembling block copolymers within the
second layer. The second direction is different from the first
direction, and may or may not be orthogonal to the first direction.
The composite pattern of the first nanoscale nested line structure
and the second nanoscale nested line structure is transferred into
an underlayer beneath the first layer to form an array of
structures containing periodicity in two directions.
[0010] According to an aspect of the present invention, a method of
forming a nanoscale pattern on a substrate is provided. The method
comprises:
[0011] forming a first recessed region having two parallel first
lengthwise edges on a first layer on a substrate;
[0012] forming a first nanoscale self-assembled self-aligned
structure containing at least one first line having a first
sublithographic width and having first line edges parallel to the
two parallel first lengthwise edges of the first recessed
region;
[0013] forming a second layer on the first nanoscale self-assembled
self-aligned structure and the first layer;
[0014] forming a second recessed region having two parallel second
lengthwise edges on the second layer, wherein an angle between the
two parallel first lengthwise edges and the two parallel second
lengthwise edges is greater than zero; and
[0015] forming a second nanoscale self-assembled self-aligned
structure containing at least one second line having a second
sublithographic width and having second line edges parallel to the
two parallel second lengthwise edges of the first recessed
region.
[0016] In one embodiment, the first nanoscale self-assembled
self-aligned structure is located at or beneath a top surface of
the first layer.
[0017] In another embodiment, the first nanoscale self-assembled
self-aligned structure is located at or beneath a top surface of
the second layer.
[0018] In even another embodiment, the method comprises applying a
first non-photosensitive polymeric resist comprising a first
polymeric component and a second polymeric component in the first
recessed region, wherein the at least one first line comprises the
first polymeric component.
[0019] In yet another embodiment, the method further comprises:
[0020] forming at least one third line having a third
sublithographic width, comprising the second polymeric component,
and laterally abutting the at least one first line in the first
recessed region; and
[0021] removing the at least one third line selective to the at
least one first line and the first layer.
[0022] In still another embodiment, the method further comprises
filling a space formed by removal of the at least one third line
with a filler material that is different from the first
non-photosensitive polymeric resist.
[0023] In a further embodiment, the method further comprises
applying a second non-photosensitive polymeric resist comprising a
third polymeric component and a fourth polymeric component in the
second recessed region, wherein the at least one second line
comprises the third polymeric component.
[0024] In an even further embodiment, the method further
comprises:
[0025] forming at least one fourth line having a fourth
sublithographic width, comprising the fourth polymeric component,
and laterally abutting the at least one second line in the second
recessed region; and
[0026] removing the at least one fourth line selective to the at
least one second line and the second layer.
[0027] In a yet further embodiment, the at least one first line
comprises a polymeric component of a first non-photosensitive
polymeric resist and the at least one second line comprises a
polymeric component of a second non-photosensitive polymeric
resist, and the method further comprises removing the second layer
selective to the at least one second line.
[0028] In a still further embodiment, the method further comprises
removing the first layer selective to the at least one first line
and the at least one second line.
[0029] In a still yet further embodiment, the method further
comprises forming a structure comprising a two dimensional array of
nanoscale trenches in an underlayer beneath the first layer and on
the substrate, wherein the nanoscale trenches are repeated along a
first direction and a second direction within the two dimensional
array, and wherein each of the nanoscale trenches has a first pair
of sidewalls separated by a first sublithographic distance and a
second pair of sidewalls separated by a second sublithographic
distance.
[0030] In further another embodiment, the first direction is
perpendicular to the two parallel first lengthwise edges, and
wherein the second direction is perpendicular to the two parallel
second lengthwise edges.
[0031] In even further another embodiment, a horizontal
cross-sectional area of the nanoscale trenches is a
parallelogram.
[0032] In yet further another embodiment, the horizontal
cross-sectional area of the nanoscale trenches is a rectangle.
[0033] According to another aspect of the present invention, a
structure comprising a two dimensional array of nanoscale trenches
in a pattern-containing layer is provided, wherein the nanoscale
trenches are repeated along a first direction and a second
direction within the two dimensional array, and wherein each of the
nanoscale trenches has a first pair of parallel sidewalls separated
by a first sublithographic distance and a second pair of parallel
sidewalls separated by a second sublithographic distance.
[0034] In one embodiment, an angle between the first direction and
the second direction is the same as an angle between one of the
first pair of parallel sidewalls and one of the second pair of
parallel sidewalls.
[0035] In another embodiment, the angle is between 0 degree and 60
degrees or between 60 degree and 90 degrees.
[0036] In even another embodiment, a horizontal cross-sectional
area of the nanoscale trenches is a parallelogram.
[0037] In yet another embodiment, the horizontal cross-sectional
area of the nanoscale trenches is a rectangle.
[0038] In still another embodiment, a first spacing between an
adjacent pair of the nanoscale trenches in the first direction is
sublithographic, and wherein a second spacing between an adjacent
pair of the nanoscale trenches in the second direction is
sublithographic.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6B, 6C,
7A, 7B, 8A, 8B, 8C, 8D, 9A, 9B, 9C, 10A, 10B, 10C, 11A, 11B, and
11C are sequential views of a first exemplary nanoscale structure
according to a first embodiment of the present invention. Figures
with the same numeric label correspond to the same stage of
manufacturing. Figures with the suffix "A" are top-down views.
Figures with the suffix "B," "C," or "D" are vertical
cross-sectional views along the plane B-B', C-C', or D-D',
respectively, of the corresponding figure with the same numeric
label and the suffix "A".
[0040] FIGS. 12A, 12B, 12C, 13A, 13B, 13C, 14A, 14B, and 14C are
sequential views of a second exemplary nanoscale structure
according to a second embodiment of the present invention. Figures
with the same numeric label correspond to the same stage of
manufacturing. Figures with the suffix "A" are top-down views.
Figures with the suffix "B" or "C" are vertical cross-sectional
views along the plane B-B' or C-C', respectively, of the
corresponding figure with the same numeric label and the suffix
"A".
DETAILED DESCRIPTION OF THE INVENTION
[0041] As stated above, the present invention relates to
two-dimensional self-assembled sublithographic nanoscale structures
in a regular periodic array and methods for manufacturing for the
same, which are now described in detail with accompanying figures.
It is noted that like and corresponding elements are referred to by
like reference numerals.
[0042] Referring to FIGS. 1A and 1B, a first exemplary nanoscale
structure according to a first embodiment of the present invention
comprises an underlayer 12 located on a substrate 10 and a first
layer 20. The substrate 10 may be a semiconductor substrate, an
insulator substrate, a metallic substrate, or a combination
thereof. The semiconductor substrate may be a silicon substrate,
other group IV element semiconductor substrate, or a compound
semiconductor Substrate. Also, the semiconductor substrate may be a
bulk substrate, a semiconductor-on-insulator (SOI) substrate, or a
hybrid substrate having a bulk portion and an SOI portion.
[0043] The underlayer 12 may comprise a semiconductor material, an
insulator material, or a metal. Exemplary material for the
semiconductor material comprises group IV elements as a pure
material or as an alloy, III-V compound semiconductor materials,
and II-VI compound semiconductor materials. The semiconductor
material may be doped with dopants, or may be substantially
undoped. Exemplary insulator materials include a dielectric oxide,
a dielectric nitride, and a porous or non-porous low-dielectric
constant dielectric material (having a dielectric constant less
than the dielectric constant of silicon oxide, i.e., less than 3.9)
known in the art. The metal may be a pure metal, an alloy of
elemental metals, a metal semiconductor alloy, or any other
conductive metal compound.
[0044] The first layer 20 may comprise a semiconductor material or
an insulator material. Exemplary semiconductor materials include
polysilicon, amorphous silicon, a polycrystalline silicon
containing alloy that includes germanium or carbon, or an amorphous
silicon containing alloy that includes germanium or silicon.
Exemplary insulator materials include a dielectric oxide, a
dielectric oxynitride, a dielectric nitride, and a porous or
non-porous low dielectric constant insulator material (having a
dielectric constant less than the dielectric constant of silicon
oxide, i.e., 3.9). Further, the first layer 20, which is a template
for the self-assembling block copolymers, may comprise amorphous
carbon or diamond-like carbon such as hydrogen-free amorphous
carbon, tetrahedral hydrogen-free amorphous carbon,
metal-containing hydrogen-free amorphous carbon, hydrogenated
amorphous carbon, tetrahedral hydrogenated amorphous carbon,
metal-containing hydrogenated amorphous carbon, and modified
hydrogenated amorphous carbon. The thickness of the first layer 20,
which may vary, is typically from about 3 nm to about 300 nm, and
typically from about 10 nm to about 100 nm.
[0045] The first layer 20 is first formed as a blanket layer
covering the entirety of a top surface of the underlayer 12, and
subsequently patterned by lithographic methods employing
application of a photoresist (not shown), patterning of the
photoresist, and an anisotropic etch that transfers the pattern in
the photoresist into the first layer 20. The pattern contains first
openings O1 in the first layer 20 beneath which the top surface of
the underlayer 12 is exposed. The first lateral width LW1 of first
openings O1 is lithographic. Further, the spacing between adjacent
first openings O1 is also lithographic. Each of the first openings
O1 has a shape of a rectangle or a parallelogram, and thus has two
lengthwise edges that are longer than widthwise edges. Preferably,
the length of the first openings O1, which is the length of the
lengthwise edges of the first openings O1, is an order of magnitude
or more longer than the width of the first openings O1, which is
the product of the length of the widthwise edges of the first
openings O1 and the sine of the angle of one of the corners of the
first openings O1.
[0046] Since the first openings O1 are formed by lithographic
methods, the length and the width of each of the first openings O1
are lithographic dimensions. Whether a dimension is a lithographic
dimension or a sublithographic dimension depends on whether the
dimension may be formed by lithographic patterning methods. The
minimum dimension that may be formed by lithographic patterning
methods is herein referred to as a "lithographic minimum
dimension," or a "critical dimension." While the lithographic
minimum dimension is defined only in relation to a given
lithography tool and normally changes from generation to generation
of semiconductor technology, it is understood that the lithographic
minimum dimension and the sublithographic dimension are to be
defined in relation to the best performance of lithography tools
available at the time of semiconductor manufacturing. As of 2007,
the lithographic minimum dimension is about 45 nm and is expected
to shrink in the future. A dimension less than the lithographic
minimum dimension is a sublithographic dimension, while a dimension
equal to or greater than the lithographic minimum dimension is a
lithographic dimension.
[0047] Referring to FIGS. 2A and 2B, a first non-photosensitive
polymeric resist is applied within each of the first openings O1 by
methods well known in the art, such as spin coating to form first
non-photosensitive polymeric resist portions 30. The top surface of
the first non-photosensitive polymeric resist portions 30 may be
coplanar with the top surface of the first layer 20, or may be
recessed below a top surface of the first layer 20. The first
non-photosensitive polymeric resist comprises self-assembling block
copolymers that are capable of self-organizing into nanometer-scale
patterns.
[0048] The first non-photosensitive polymeric resist comprises a
first polymeric block component and a second polymeric block
component that are immiscible with each other. The
non-photosensitive polymeric resist may be self-planarizing.
Alternatively, the non-photosensitive polymeric resist may be
planarized by chemical mechanical planarization, a recess etch, or
a combination thereof.
[0049] Exemplary materials for the first polymeric block component
and the second polymeric block component are described in
commonly-assigned, copending U.S. patent application Ser. No.
11/424,963, filed on Jun. 19, 2006, the contents of which are
incorporated herein by reference. Specific examples of
self-assembling block copolymers for the non-photosensitive
polymeric resist that can be used for forming the structural units
of the present invention may include, but are not limited to:
polystyrene-block-polymethylmethacrylate (PS-b-PMMA),
polystyrene-block-polyisoprene (PS-b-PI),
polystyrene-block-polybutadiene (PS-b-PBD),
polystyrene-block-polyvinylpyridine (PS-b-PVP),
polystyrene-block-polyethyleneoxide (PS-b-PEO),
polystyrene-block-polyethylene (PS-b-PE),
polystyrene-b-polyorganosilicate (PS-b-POS),
polystyrene-block-polyferrocenyldimethylsilane (PS-b-PFS),
polyethyleneoxide-block-polyisoprene (PEO-b-PI),
polyethyleneoxide-block-polybutadiene (PEO-b-PBD),
polyethyleneoxide-block-polymethylmethacrylate (PEO-b-PMMA),
polyethyleneoxide-block-polyethylethylene (PEO-b-PEE),
polybutadiene-block-polyvinylpyridine (PBD-b-PVP), and
polyisoprene-block-polymethylmethacrylate (P1-b-PMMA).
[0050] The self-assembling block copolymers are first dissolved in
a suitable solvent system to form a block copolymer solution, which
is then applied onto the surface of the first exemplary structure
to form the non-photosensitive polymeric resist. The solvent system
used for dissolving the block copolymer and forming the block
copolymer solution may comprise any suitable solvent, including,
but not limited to: toluene, propylene glycol monomethyl ether
acetate (PGMEA), propylene glycol monomethyl ether (PGME), and
acetone. The non-photosensitive polymeric resist is not a
conventional photoresist that may be developed upon exposure to
ultraviolet light or optical light. Also, the non-photosensitive
polymeric resist is not a conventional low-k dielectric
material.
[0051] Referring to FIGS. 3A and 3B, a first nanoscale
self-assembled self-aligned structure NS1 is formed within each of
the first openings O1 (See FIG. 1B) by causing cross-linking of the
self-assembling block copolymers through annealing. Specifically,
the first non-photosensitive polymeric resist is annealed by
ultraviolet treatment or by thermal annealing at an elevated
temperature to faun first primary lamellar structures 40 comprising
the first polymeric block component and first complementary
lamellar structures 50 comprising the second polymeric block
component. The first primary lamellar structure 40 and the first
complementary lamellar structures 50 alternate with periodicity in
the direction perpendicular to the lengthwise direction of the
first openings O1.
[0052] Exemplary processes of annealing the self-assembling block
copolymers in the block copolymer layer to form two sets of polymer
blocks are described in Nealey et al., "Self-assembling resists for
nanolithography," IEDM Technical Digest, December, 2005, Digital
Object Identifier 10.1109/IEDM.2005.1609349, the contents of which
are incorporated herein by reference. Methods of annealing
described in the '963 Application may be employed. The anneal may
be performed, for example, at a temperature from about 200.degree.
C. to about 300.degree. C. for a duration from less than about 1
hour to about 100 hours.
[0053] The composition and wetting properties of the first
non-photosensitive polymeric resist is adjusted such that some of
the first primary lamellar structures 40 abut the sidewalls of the
first layer 20, while the first complementary lamellar structures
50 are disjoined from the sidewalls of the first layer 20. The
wetting characteristics of the first polymeric block component may
be tuned so that the width of a first primary lamellar structure 40
depends on whether the first primary lamellar structure 40 contacts
the sidewalls of the first layer 20 or not. For example, the width
of a first primary lamellar structure 40 that does not contact the
sidewalls of the first layer 20 may be the same as, or different
from, the width of a first primary lamellar structure 40 that
contacts the sidewalls of the first layer 20. The width of the
first primary lamellar structures 40 may be sublithographic, and in
the range from about 1 nm to about 40 nm, and typically from about
5 nm to about 30 nm. The width of the first complementary lamellar
structures 50, which is herein referred to as a first lamellar
spacing, may be sublithographic. The sum of the width of one of the
first primary lamellar structures 40 and the first lamellar spacing
may also be sublithographic.
[0054] The first nanoscale self-assembled self-aligned structures
NS1 are "self-assembled." The chemical composition of the first
non-photosensitive polymeric resist is such that the immiscibility
of the first and second polymeric block components enable self
assembly of the first polymeric block component into the first
primary lamellar structures 40 and the second polymeric block
component assembles into the first complementary lamellar
structures 50.
[0055] The first nanoscale self-assembled self-aligned structures
NS1 are "self-aligned" to the walls of the first layer 20 that
define the first openings O1. The first primary lamellar structures
40 and first complementary lamellar structures 50 run along the
lengthwise direction of the first openings O1 in the first layer
20.
[0056] Referring to FIGS. 4A and 4B, the first complementary
lamellar structures 50 are removed selective to the first primary
lamellar structures 40 and the first layer 20 by an anisotropic
etch that removes the second polymeric block component selective to
the first polymeric block component. A set of first primary
lamellar structures 40 constitutes within each of the first
openings O1 (See FIG. 1B) constitutes a first one dimensional
arrays of parallel lines having a sublithographic width and a
sublithographic spacing. Variations of the present invention in
which the first primary lamellar structures 40 are removed
selective to the first complementary lamellar structures 50 and the
first layer 20 by an anisotropic etch that removes the first
polymeric block component selective to the second polymeric block
component are explicitly contemplated herein.
[0057] Referring to FIGS. 5A and 5B, filler portions 22 are formed
between the first primary lamellar structures 40. The filler
portions 22 comprise a material that may be removed selective to
the first primary lamellar structures 40 comprising the first
polymeric block component. For example, the filler portions may
comprise a dielectric oxide, a dielectric nitride, or a porous or
non-porous low dielectric constant material (having a dielectric
constant less than the dielectric constant of silicon oxide, i.e.,
3.9). The filler portions 22 may be formed by spin-on coating,
deposition and recess etch, deposition and chemical mechanical
planarization (CMP), or a combination thereof.
[0058] Referring to FIGS. 6A-6C, a second layer 60 is formed as a
blanket layer directly on the first layer 20, the first primary
lamellar structures 40, and the filler portions 22. The second
layer 60 may comprise any of the material that may be employed as
the first layer 20. Specifically, the second layer 60 may comprise
a semiconductor material, an insulator material, amorphous carbon,
or diamond-like carbon. A spin-on coating or chemical vapor
deposition may be employed to form the second layer 60. The
thickness of the second layer 60 may be from about 3 nm to about
600 nm, and typically from about 10 nm to about 200 nm.
[0059] In a variation of the first embodiment, the filler portion
22 and the second layer 60 may comprise the same material, and may
be formed at the same processing step by forming the second layer
60 between the first primary lamellar structures 40. In this case,
the filler portion 22 and the second layer 60 are integrally formed
without any manifested physical interface therebetween.
[0060] The second layer 60 is patterned by lithographic methods
employing application of a photoresist (not shown), patterning of
the photoresist, and an anisotropic etch that transfers the pattern
in the photoresist into the second layer 60. The pattern contains a
second opening O2 in the second layer 20. The second opening O2 may
be formed through the second layer 60 to expose a top surface of
the first layer 20, the first primary lamellar structures 40, and
the filler portions 22, or alternately, may be formed only partly
into the second layer 60 without exposing a top surface of the
first layer 20.
[0061] A second lateral width LW2, which is the lateral width of
the second opening O2, is lithographic. More than one second
opening O2 may be formed. In such a case, the spacing between
adjacent second openings O2 is also lithographic. The second
opening O2 has a shape of a rectangle or a parallelogram, and thus
has two lengthwise edges that are longer than widthwise edges.
Preferably, the length of the second opening O2, which is the
length of the lengthwise edges of the second openings O2, is an
order of magnitude or more longer than the width of the second
opening O2, which is the product of the length of the widthwise
edges of the second opening O2 and the sine of the angle of one of
the corners of the second opening O2. Since the second opening O2
is formed by lithographic methods, the length and the width of the
second opening are lithographic dimensions.
[0062] Referring to FIGS. 7A and 7B, a second non-photosensitive
polymeric resist is applied within the second opening O2 by methods
well known in the art, such as spin coating to form second
non-photosensitive polymeric resist portions 80. Preferably, the
top surface of the second non-photosensitive polymeric resist
portions 80 may be recessed below, or substantially level with, the
top surface of the second layer 60 outside the second opening O2.
The second non-photosensitive polymeric resist may be applied to be
coplanar with, or above, the top surfaces of the second layer 60,
and then recessed to a final height by a recess etch, or by
employing a dilute solution from which subsequent evaporation of a
solvent causes volume contraction within the second opening O2.
[0063] The second non-photosensitive polymeric resist comprises
self-assembling block copolymers that are capable of
self-organizing into nanometer-scale patterns. Thus, any of the
material listed above for the first non-photosensitive polymeric
resist may be employed for the second non-photosensitive polymeric
resist. The second non-photosensitive polymeric resist may comprise
the same material as, or a different material from the first
photosensitive polymeric resist. For the purposes of illustrating
the present invention, the polymeric block components of the second
non-photosensitive polymeric resist are referred to as a third
polymeric block component and a fourth polymeric block component.
The third polymeric block component may be the same as, or
different from, the first polymeric block component. Likewise, the
fourth polymeric block component may the sane as, or different
from, the second polymeric block component.
[0064] Referring to FIGS. 8A-8D, a second nanoscale self-assembled
self-aligned structure NS2 is formed within the second opening O2
by causing cross-linking of the self-assembling block copolymers
through annealing. The same method employed for the formation of
the first nanoscale self-assembled self-aligned structure NS1 may
be employed to form the second nanoscale self-assembled
self-aligned structures NS2.
[0065] Specifically, the second non-photosensitive polymeric resist
is annealed by ultraviolet treatment or by thermal annealing at an
elevated temperature to form second primary lamellar structures 90
comprising the third polymeric block component and second
complementary lamellar structures 100 comprising the fourth
polymeric block component. The second primary lamellar structure 90
and the second complementary lamellar structures 100 alternate with
periodicity in the direction of the second lateral width LW2, i.e.,
in the direction perpendicular to the lengthwise edges of the
second opening O2.
[0066] The composition and wetting properties of the second
non-photosensitive polymeric resist is adjusted such that some of
the second primary lamellar structures 90 abut the sidewalls of the
second opening O2 in the second layer 60, while the second
complementary lamellar structures 100 are disjoined from the
sidewalls of the second opening O2 in the second layer 60. The
wetting characteristics of the third polymeric block component is
tuned so that the width of a second primary lamellar structure 90
abutting the sidewalls of the second opening O2 in the second layer
60 may be the same as, or different from, the width of another
second primary lamellar structure 90 disjoined from the sidewalls
of the second opening O2 in the second layer 60.
[0067] The width of the second primary lamellar structures 90 may
be sublithographic, and in the range from about 1 nm to about 40
nm, and typically from about 5 nm to about 30 nm. The width of the
second complementary lamellar structures 100, which is herein
referred to as a second lamellar spacing, may be sublithographic.
The sum of the width of one of the second primary lamellar
structures 90 and the second lamellar spacing may also be
sublithographic.
[0068] The second nanoscale self-assembled self-aligned structures
NS2 are self-assembled and self-aligned in the same sense that the
first nanoscale self-assembled self-aligned structures NS1 are
self-assembled and self-aligned, since the same mechanism is
employed for the self-assembly and self-alignment of the various
components of the second nanoscale self-assembled self-aligned
structures NS2.
[0069] Referring to FIGS. 9A-9C, the second complementary lamellar
structure 100 and the exposed portions of the second layer 60 are
removed selective to the second primary lamellar structures 90 by
an anisotropic etch such as a reactive ion etch. Top surfaces of
the first layer 20, the filler portions 22, and the first primary
lamellar structures 40 are exposed after the anisotropic etch.
Thus, the second primary lamellar structures 90 are employed as an
etch mask that contains a one dimensional array of lines having a
sublithographic width and a sublithographic spacing. Variations of
the present invention in which the second primary lamellar
structure 90 and the exposed portions of the second layer 60 are
removed selective to the second complementary lamellar structures
100 by an anisotropic etch such as a reactive ion etch are
explicitly contemplated herein.
[0070] Referring to FIGS. 10A-10C, the filler portions 22, the
first layer 20 and the underlayer 12 are etched by an anisotropic
etch such as a reactive ion etch selective to the second primary
lamellar structures 90 and the first primary lamellar structures
40. The underlayer 12, as patterned with the patterns of the second
primary lamellar structures 90 and the first primary lamellar
structures 40, is herein referred to as a pattern-containing layer
12'.
[0071] Referring to FIGS. 11A-11C, the second primary lamellar
structures 90 and the first primary lamellar structures 40 as well
as any remaining portions of the second layer 60, the filler
portions 22, the first layer 20 that are located directly beneath
the second primary lamellar structures 90 are removed selective to
the pattern-containing layer 12' and the substrate 10.
[0072] The pattern-containing layer 12' contains a plurality of
nanoscale trenches having nanoscale dimensions, which is typically
sublithographic. The pattern of the trench is formed by
juxtaposition of two patterns having a periodicity in two different
directions. The first pattern comprises the pattern of the first
primary lamellar structures 40 containing a first set of
sublithographic width lines separated by a sublithographic spacing,
which is the first lamellar spacing, and repeated in the direction
perpendicular to the lengthwise edges of the first openings O1 (See
FIG. 1B), which is herein referred to as a first direction. The
second pattern comprises the pattern of the second primary lamellar
structures 90 containing a second set of sublithographic width
lines separated by another sublithographic spacing, which is the
second lamellar spacing, and repeated in the direction
perpendicular to the lengthwise edges of the second opening O2 (See
FIG. 6C), which is herein referred to as a second direction.
[0073] The nanoscale trenches in the pattern-containing layer 12'
is arranged in a two dimensional rectangular array or a two
dimensional parallelogram-lattice array. The nanoscale trenches are
repeated along the first direction and the second direction within
the two dimensional array. Each of the nanoscale trenches has two
pairs of sidewalls having a nanoscale dimension, i.e., a dimension
from about 1 nm to about 40 nm, and typically from about 5 nm to
about 30 nm.
[0074] Referring to FIGS. 12A-12C, a second exemplary nanoscale
structure according to a second embodiment of the present invention
is derived from the first exemplary nanoscale structure of FIGS.
9A-9C by removing the filler portions 22 and the underlayer 12 by
an anisotropic etch such as a reactive ion etch selective to the
first layer 20, the second primary lamellar structures 90, and the
first primary lamellar structures 40. The underlayer 12, as
patterned with the patterns of the second primary lamellar
structures 90 and the first primary lamellar structures 40, is
herein referred to as a pattern-containing layer 12'.
[0075] According to the second embodiment, only the portion of the
pattern of the second primary lamellar structures 90 within the
area of the first openings (See FIG. 1B) are transferred into the
pattern-containing layer 12' since the first layer 20 functions as
an etch mask in combination with the second primary lamellar
structures 90 and the first primary lamellar structures 40.
[0076] Referring to FIGS. 13A-13C, the first layer 20, the first
primary lamellar structures 40, and the second primary lamellar
structures 90 as well as any remaining portions of the second layer
60, the filler portions 22, the first layer 20 that are located
directly beneath the second primary lamellar structures 90 are
removed selective to the pattern-containing layer 12' and the
substrate 10.
[0077] The pattern-containing layer 12' contains a plurality of
nanoscale trenches having nanoscale dimensions, which is typically
sublithographic. The pattern of the trench is formed by
juxtaposition of two patterns having a periodicity in two different
directions. The first pattern comprises the pattern of the first
primary lamellar structures 40 containing a first set of
sublithographic width lines separated by a sublithographic spacing,
which is the first lamellar spacing, and repeated in the direction
perpendicular to the lengthwise edges of the first openings O1 (See
FIG. 1B), which is herein referred to as a first direction. The
second pattern comprises the pattern of the second primary lamellar
structures 90 containing a second set of sublithographic width
lines separated by another sublithographic spacing, which is the
second lamellar spacing, and repeated in the direction
perpendicular to the lengthwise edges of the second opening O2 (See
FIG. 6C), which is herein referred to as a second direction.
[0078] The nanoscale trenches in the pattern-containing layer 12'
is arranged in a two dimensional rectangular array or a two
dimensional parallelogram-lattice array. The nanoscale trenches are
repeated along the first direction and the second direction within
the two dimensional array. Each of the nanoscale trenches has two
pairs of sidewalls having a nanoscale dimension, i.e., a dimension
from about 1 nm to about 40 nm, and typically from about 5 nm to
about 30 nm. The nanoscale trenches may have a rectangular
horizontal cross-sectional area.
[0079] Referring to FIGS. 14A-14C, a generalized variation of the
second exemplary nanoscale structure comprises a two dimensional
parallelogram-lattice array of nanoscale trenches. Each of the
nanoscale trenches has a set of first trench walls TW1 separated by
a first width W1. A pair of first trench walls TW1 belonging to an
adjacent pair of nanoscale trenches in the first direction, i.e.,
in the direction of the first nanoscale width W1, is separated by a
first spacing S1. Each of the first width W1 and the first spacing
S1 is a nanoscale dimension, e.g., from about 1 nm to about 40 nm,
and typically from about 5 nm to about 30 nm. Likewise, each of the
nanoscale trenches has a set of second trench walls TW2 separated
by a second width W2. A pair of second trench walls TW2 belonging
to an adjacent pair of nanoscale trenches in the second direction,
i.e., in the direction of the second nanoscale width W2, is
separated by a second spacing S2. Each of the second width W2 and
the second spacing S2 is a nanoscale dimension, e.g., from about 1
nm to about 40 nm, and typically from about 5 nm to about 30
nm.
[0080] The angle .alpha. between the first direction and the second
direction may be any arbitrary angle other than zero. For example,
the angle .alpha. may be between 0 degree and 60 degrees, 60
degrees, between 60 degrees and 90 degrees, or 90 degrees. The
angle .alpha. between the first direction and the second direction
is the same as an angle of a corner of a horizontal cross-sectional
area of one of the nanoscale trenches, which is a parallelogram.
Thus, the present invention enables an array of nanoscale trenches
having sublithographic dimensions on the substrate 10.
[0081] While the invention has been described in terms of specific
embodiments, it is evident in view of the foregoing description
that numerous alternatives, modifications and variations will be
apparent to those skilled in the art. Accordingly, the invention is
intended to encompass all such alternatives, modifications and
variations which fall within the scope and spirit of the invention
and the following claims.
* * * * *